How to configure Asterisk to send audio before call is establishedThanks for your answer. That is pretty much what I've pieced together from mailing list posts and bug reports I found online. What I am trying to do is send early voice while receiving early media from the remote party before they answer. So they are the ones that answer and I can't control that. I will experiment with the 'd|D' options, thanks for the hint. As for the actual SIP phone, it can send early voice, I can record voice using Asterisk without sending an OK. Most examples deal with early media when the target is Asterisk, as does the wiki you linked.

How to configure Asterisk to send audio before call is establishedThis seems to work when the target is Asterisk with something like NoOP(test) Progress() SayAlpha(asdf) Wait(20) ... This give audio in both directions without establishing the call. Still not sure what is needed to get it working when calling an actual remote party.

How to configure Asterisk to send audio before call is establishedAt least RFC3960 defines this: 'Early media refers to media (e.g., audio and video) that is exchanged before a particular session is accepted by the called user. (...) It may be unidirectional or bidirectional, and can be generated by the caller, the callee, or both.'